Resistance bands, suspension straps and stretch straps have become popular among exercisers, personal trainers and physical therapist alike. As simple, low cost devices and an alternative to high cost weight systems, they have become a standard piece of exercise equipment in any gym or physical therapy office.
There are two commonly used forms of resistance bands. The most common resistance band consists of rubber tubing of about five feet in length with handles on one end and a connector at the other end to secure the resistance band to an anchoring device. Another type of resistance band is a flat band about four inches wide that comes in rolls. The flat bands are most commonly used in physical therapy where varying lengths and strengths are cut and used for therapeutic exercises.
Suspension straps have recently grown in popularity, particularly for bodyweight training. Such suspension straps are usually made of nylon anchored to a fixed object and are of sufficient strength to support a person's weight. They generally consist of three components. On one end, there is the anchoring portion of the strap, usually a clip of some type. The middle portion is several feet of nylon strap to support a person's weight. At the other end, there is a handle. In a gym setting, suspension straps are typically anchored to the ceiling, A-frames, weight machines, walls and, sometimes, the floor. The user usually fastens the suspension strap to the anchoring device by either wrapping the strap around the anchoring device or locking it into place with a carabineer or with a clip hook connected directly to a closed loop anchor. These straps can be adjusted by either buckles or strap extenders. Although there are many companies marketing and selling suspension straps, the most popular is the TRX™ Suspension Trainer™ from Anytime Fitness.
Another popular therapeutic exercise device is the stretch strap. To use a stretch strap, the body is put into a lever position to lengthen the muscle being stretched. A buckle is used to form a closed loop at one end to anchor the strap to a foot or wrist. Once the foot or wrist is anchored, the user pulls the other end of the strap to execute the stretch.
There are a number of key deficiencies in these three forms of exercise bands. Many of these exercise bands have open loops, slings, or handles that do not properly secure the limb, extremity or torso. This is particularly true among the “ab” or ankle straps. When strapped in the vertical position, for example, a person can easily fall out of such loop, sling or handle. Furthermore, an open loop, sling or handle puts a tremendous amount of pressure on the joints and, in many cases, may cause injury to joints. This is particularly a problem with people having weaker joints or a weak grip. If a person has a weak joint, it further exposes them to injuries, especially, injury to the elbow, ankle or knee joints. Whether it's the TRX, cables, or free weights, the user must use either the wrist or ankle joint to apply resistance to the more proximal muscle group or trunk/core muscles. Hence the smallest, weakest, and most distal joints are almost always used. Additionally, when comparing a force vector analysis of a movement such as a bench press, the total resistance applied at the palm is dissipated as it reaches the chest. Any weakness of any joint in the path will then set the upper limit on how much resistance can be delivered to the target muscle. Since the plane of movement of the upper extremity, for example, is limited by the sum of all the other joints, such as the elbow and shoulder, the angle of force is more in the horizontal plane. Moreover, the current exercise band design does not transfer the suspended weight directly to the core muscle group that is of interest to build or strengthen.